Cannot send emails. Emails coming in but when I send they are just being held in outbox. Fix report says smtp error

Completely disable your anti-virus and firewall and try again.

Tried that. Did not work.

Are the SMTP settings correct? What is the fix report error?

pop3 ok but smtp error trying to fix but not working either

nothing. just little circle running round. no log

Who is your email provider?

11:46:15     "The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters. 

Was Tiscali now Talk Talk

Try these settings in SMTP

Host: smtp.talktalk.net
Port: 465
Security Policy:  Use SSL/TLS on special port (legacy)

You can also try

Host: smtp.talktalk.net
Port: 25
Security Policy:  Use SSL/TLS if available

Actually it must have been a server fault cos it rectified later that day. Been ok since